Fig. 5: Model and experimental evaluation of SAM-VI riboswitch sequential folding and translational control.
From: SAM-VI riboswitch structure and signature for ligand discrimination
a Sequential folding path highlighted for two transcriptional intermediates of critical length, metK 61 and metK 65; mutually exclusive secondary structures with competing P0 and P1 stems are shown and the expected response in the presence of SAM. b RNA sequences used for the 2-aminopurine fluorescence assays. c Fluorescence changes of UAp39 labeled SAM-VI riboswitch variants (metK 61 and metK 65; c(RNA) = 0.5 µM) upon addition of saturating concentration of ligand SAM (15 µM). d Organization of SAM-VI riboswitch lacZ reporter construct in E. coli and RNA sequences with mutations indicated used for β-galactosidase assays. e In vivo expression analysis of the wild-type and mutant E. coli metK RNAs. ß-Galactosidase activities are presented as normalized gene expression relative to WT. Representative results of three experiments are shown (mean ± standard error of the mean).
